MEPS 314:127-133 (2006)  -  doi:10.3354/meps314127

ABSTRACT: Oxygen isotope compositions of Porites sp. were measured in order to examine the effect of the 1998 bleaching event on the skeletal record of 6 neighboring colonies from Sesoko Island, Okinawa, Japan. A δ¹⁸O_c–SST dependency of 0.18‰/°C was calculated using a 10 yr record, well within accepted calibrations. The skeleton portion accreted during 1998 exhibited 0.3‰ enrichment in δ¹⁸O, which differs from the depleted values expected during abnormally high SST conditions. Growth rate changed significantly during the bleaching event, and its manifestation in skeletal δ¹⁸O masked the temperature signal. The δ¹⁸O variance among the 6 colonies was noticeably higher during 1998 in comparison with 1997 and 1999. A residual analysis revealed that 75% of the inter-annual variation of the δ¹⁸O record is explained by variation in annual extension rate. The increase in δ¹⁸O variance is proposed as a novel indicator for stressful environmental conditions.

KEY WORDS: Coral · Stable isotopes · Sea surface temperature · Bleaching